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YOUR RESEARCHWho's done an AOS without a motor drop?
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only way
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When my transmission was dropped for the IMS Solution install on my car, the mechanic installed the AOS from the flywheel side of the engine.
Replace aos and the two coolant lines last week due
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I replaced the AOS and the two coolant lines last week due to it leaking coolant.
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As I replaced the AOS I contemplated the idea of doing that job with the engine in.
Replace coolant hoses, clamps etc at the same time fwiw
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I replaced all my coolant hoses, clamps etc at the same time FWIW.
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No. Just the left intake manifold. The most challenging parts are the two bolts. One closest to the front that bolts down the left intake manifold. The other closest to the rear bolting down the AOS, which needs to be attacked from the bottom.
Yes, I remember the challenge of that last manifold bolt. Short open ended wrench a little at a time if I recall.
Thanks!
A catch can sounds more and more attractive...
Yeah, after seeing your thread, I think I'm going to pull the trigger on designing and machining one that will fit nicely in our engine bay. My current thought is to have it mount directly on the intake plenum to keep it compact as possible.
Truly it's a really unsatisfying job, so much groveling around working by feel. I did remove (and replace) the expansion tank and getting it back in was even worse than the damn blind bolt on the AOS. I replaced all my coolant hoses, clamps etc at the same time FWIW. If I ever have to do this again I'll drop the engine even though it is a much bigger job, just because I'll learn a bunch more and it will be more satisfying.
BTW Ahsai, your AOS replacement notes were super useful...thanks!
It sucks but I got it done on my previous C2. Like tying your shoes while reaching through a toilet paper roll.
Takes patience and a wide assortment of tools and wobbles in different lengths and angles.
Having access through the engine bay, as well as from the left front of the engine (left front wheel-well area) is critical.
Do your coolant tank at the same time if it's not new.
No tips or tricks - just an opinion....
Install a catch can as a temporary solution. Then when the time comes to drop the engine for a bigger issue, replace the AOS then and only then.
This is my current plan, since I am in a similar boat. I'm looking at making my catch can installation cleaner and more robust. One thing I have not yet decided, is where to route the outlet from the catch can. I think it should go in either the air box snorkel or near the ventilation holes at the right side of the air box. Any one here have thoughts on these two ideas?
I had my engine out a year ago for the standard bunch of work (IMS Solution, RMS, clutch, etc.).
As I replaced the AOS I contemplated the idea of doing that job with the engine in. My hat's off to anyone who manages this.
If you remove the Transmission support, rear suspension cross brace and sway bar, you can lower the engine about 4" without removing much else (I did this in order to remove the bank II cam cover). I think this will get you enough room to make the AOS swap easier, though I can't speak directly to that job, as I did mine while my engine was out... Good luck!
My state does annual safety and emissions (more like revenue generation) inspections and they�ve gotten really strict over the last couple of years. I don�t think a catch can would pass unless it wasn�t noticed. Do other states not have this kind if thing?
Some areas of Texas have emission testing requirements. (Counties with large cities and the surrounding counties)
But there are no visual inspections.
If the computer is happy, they're happy.
All cars 24 years old and newer have to be inspected.
Cars without OBDII had to have testing on a dyno.
This is the last year of that, next year all non-OBDII vehicles will be exempt.
For the last several years it has been almost impossible to find a place that does non-OBDII testing.
It requires a "special" emissions dyno that no shops have anymore, or if they have one they don't want to get them repaired since the phase out has made it where there are fewer and fewer older cars needing inspection.
There is just one that I know of in the Houston area. (in tiny Rosenberg)
Going forward, I'm not sure if the 24 year old rule will continue to apply, or if they will change to say all cars with OBDII will need to be inspected.
I'm hoping they will stay with 24 years old and newer so that someday my 996 will no longer need the emissions testing.
I'd like to save on the inspection cost, and also be able to go cat-less without worry.
Safety inspection for exempt non-OBD vehicles: $7.50
Safety inspection & emissions testing for OBDII vehicles: $39.75
My friend's 1995 Vette failed emissions 4 times this year.
EGR valve, and 2 replacement valves kept barely failing.
When you fail, then the requirements are harder the next time.
He finally passed, and is now in the process of removing all his emissions equipment.
They make it look so damn easy in the Porsche factory - the body comes from one side, the engine assembly from another and voila.
I'm not sure how many of those 3 minute stations it takes but it's done quicker than most deep dish pizzas.
I've done the AOS replacement in-situ. Total PITA. I've expressed my opinions and tips on other AOS replacement threads. The things to add are: beer, advil, bandages, ace wrap your left arm, cuss like a sailor, walk away when totally frustrated and have another beer (helps kill the pain in your left arm and fingers).
Glad to hear my notes helped. I've done in from the top and from the bottom (with transmission removed). Neither way is a walk in the park. At least not for an MkII.
I would try to find an excuse to drop the 996 engine for this job. Something like: clutch, IMS, exhaust, water pump, coolant tank, and spark plugs. Those things would be so much easier with the engine out....
I replaced the AOS and the two coolant lines last week due to it leaking coolant. Lowered the motor at the mounts for access found the biggest PITA is the back bolt on the intake manifold. I'd recommend ordering 3 intake gaskets, a new oil fill tube and the coolant connector by the alternator your bound to break.
Looks like a pain, Pelican has a decent right up though. I am sort of glad I need to do the RMS, AOS and clutch, more reason to just pay someone to drop the engine and throw in the IMS while they are there. Otherwise, I would spend 8 hours in the garage cursing at the AOS.
Yea, I hear you! I understand wanting to get the job done quickly and not wasting any money thinking the old AOS should be fine. When my transmission was dropped for the IMS Solution install on my car, the mechanic installed the AOS from the flywheel side of the engine. The engine was also dropped as low as it would go and he said it's still a PITA to work on.
I haven't read back on all the posts, but I'm glad to hear your car isn't totally toast. It's good when people come together to support and help a man in need. That's the way it used to be. Can tell you how many times, people helped us on the old Chevy and Fords, but not too many people around that know anything about Porsches. Fortunately, the internet and Porsche forums have been a super help for the average DIYer.
Did you determine one way or the other if any of the connecting rods were bent?
I need to do mine, but lately I�ve been working 6 days a week (up to 16 hour days) and I just don�t feel like working on my own car on my day off.
Last weekend was supposed to be a 4 day weekend and ended up as 1 1/4.
I spent that 1.25 day at church and sleeping.
Plus there are so many other things that need to get done around the house that a long repair job is far down the list.
I�ve been thinking about paying to have it done.
The posts above are helping to convince me.
Not sure how you could check on the rods but the car has been driving as normal. Seems to rev up the RPM range a little quicker without the AOS attached (maybe my imagination)
Parts came in yesterday so I'm going in on Tuesday as I have 3 days off and can take my time.
Wish me luck!
Again, thanks for all the support... best group of car guys ever!
What a cluster F@#$%! this has turned into...Got almost everything apart but can't get the farthest forward manifold bolt off So I moved under to see if I could get the hoses off the AOS and discovered the one VERTEX sent me is the wrong (AOS) one!
Thank you. I've been at it for five hours and feel like I've gotten nowhere. Then it looks like I got the wrong AOS as mine looks to mount on top and not the side like I've seen in that thread.
It's midnight and I'm going to lower the motor in the morning...
It took me 3 painstaking days. Take your time...it can be done. I know the last forward manifold bolt is a total PITA. I went over the top of the manifold and down with all types of swivel joints and extensions. I used painters tape to hold everything together and reached in blind with my left hand to get it on the bolt. It is a long way back there. Damn thing was, once I got it loose enough to come out with my fingers, I dropped it and it didn't fall on the garage floor. I was determined to find it and it took me three days total to do this job. The offending SOB finally out:
808Bill, I'm sorry to hear about your frustration. I've heard of the mismatch part fiasco before. A person goes to the parts store to order a part like your AOS, gives them the VIN number, but the part doesn't fit because the motor is not the exact one that was installed at the factory. Maybe that's the case with your motor?
I'm just glad I got my changed out with the clutch service. I remember the mechanic giving me "the face" when explaining how much of a PITA it is to install these simple little parts.
I don't have a lift or the capability of dropping the engine in my garage. I did drop it down to the cross-member. When the AOS is the only problem part that needs to replaced (mine was weeping coolant), I don't see it as practical to drop the entire engine just for that, so about the only option is to go in from the top.
Oh you have no fricken idea! Just start by lowering it as there is no other way on my 02 with 3.6. Also, you need to be nimble handed and able to wrench with both hands and sometimes use only two fingers.
I made a huge mistake when I put the motor in. My rear right plenum clamps where facing the front of the car
Also, I can't pinch the AOS line from the bottom and get any leverage to pull it off, my forearms are two big for this job.
Pelican Tech articles are good but one size does not fit all...Nor is there any info in the Bentley Manual. I hade remove a cam position sensor (I think) bracket and ground wire to gain some room underside bank one. You need the flex cable type hose clamp tool to do this job too.
Nutty, the Amazon listing said "Fits 996" and also has 996 in the part number. Until I got up under the car and started unhooking hoses, I noticed mine had 3 and the new one had 2, and different mounting points. Vertex is going to correct that and a new part is on it's way. It just sucks that I now won't have my cars use till next week (I'm not putting it back together just to start over.
So, stay tunned!
I am having my IMSB replaced (preventively) and the shop said they still attack the AOS through the deck lid top of motor.
I always thought with trans out you would go that direction.
I'd love to know how they do that without lowering the motor. There is just no way that I can see to get the last manifold bolt out other than over the top of the motor.
Have you removed the two bolts holding down the AOS successfully yet? You need to do that first and move the AOS up to create clearance for tools on that last intake manifold bolt.
l lowered the motor and there is no way I'm getting a socket on that bolt. I now remember I had to use a box wrench for that one when the motor was out. No room to get a short box wrench in there now either. Is the AOS or something else hovering over that bolt?
Yes, the AOS u-channel and/or engine harness is blocking that bolt completely.
Have you checked my write-up here?
https://rennlist.com/forums/996-foru...i-aos-diy.html
Maybe why they want 1k to do aos only even with trans out
they tell me its a big job and dont do it until it fails
big 996 race shop so I like their opinion
Ahsai - your write-up is for a MKII. Can you define how this would differ from MKI AOS?
I didn't get through it, so forgive me if you explain the difference in the write-up. I'm in a hurry to get out of work, so I can go home and play with my own toys....
I have not worked on an MkI AOS (Thank goodness) but the process/concept should be similar. The trick is HOW to get to that last manifold bolt. I think it's easier because the MkI AOS does not have the u-channel on it blocking the manifold bot.
One difference is an MkII AOS goes on from the top and the MkI AOS goes on from the side (L-shape drain port). Also you need to deal with the accordian boot.
Just to give you a visual of what are in the way for that last intake manifld bolt. It's burried under the AOS u-channel and thick engine harness (which you have to cut the zip tie to move it out of the way).
And the angels sang...Halleluiah!!
1/16 at a time. Short box wrench was the only way. Thank God I'm good with my hands. This was harder than eating rice with chopsticks with your left hand!
I can't get the AOS line off nor can I get to the second anchor bolt (10mm) holding the AOS to the block. Socket won't seat and box wrench seems (space wise) worst then the manifold bolt.
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